Gas sensor with a resonant element, method for producing the same and use of the same for detecting gases

Abstract

A method for producing a gas sensor includes providing a substrate; depositing a semiconductor-based layer on the substrate; producing a first sensor element in the semiconductor-based layer, the first sensor element forming a resonant element; and mounting a cover on the first sensor element, where at least one of the substrate or the cover includes an opening to allow a passage of a gas to the first sensor element

1 . A method for producing a gas sensor, the method comprising:
 providing a substrate;   depositing a semiconductor-based layer on the substrate;   producing a first sensor element in the semiconductor-based layer, the first sensor element forming a resonant element; and   mounting a cover on the first sensor element, wherein at least one of the substrate or the cover includes an opening to allow a passage of a gas to the first sensor element.   
     
     
         2 . The method as claimed in  claim 1 , wherein the resonant element has a shape of a tuning fork or a single beam. 
     
     
         3 . The method as claimed in  claim 1 , the method further comprising:
 producing a second sensor element in the semiconductor-based layer, the second sensor element forming an acoustic resonator in the semiconductor-based layer.   
     
     
         4 . The method as claimed in  claim 3 , the method further comprising:
 producing an additional semiconductor-based sensor element laterally next to the first sensor element and the second sensor element.   
     
     
         5 . The method as claimed in  claim 4 , wherein at least one of the first sensor element, the second sensor element, or the additional semiconductor-based sensor element are produced as MEMS components. 
     
     
         6 . The method as claimed in  claim 1 , wherein the cover is mounted onto the first sensor element using wafer bonding or anodic bonding. 
     
     
         7 . The method as claimed in  claim 1 , further comprising:
 utilizing the gas sensor to detect hydrogen.   
     
     
         8 . The method as claimed in  claim 7 , wherein the gas sensor is utilized in a container in which gaseous hydrogen is stored or transported or in pipes in which the gaseous hydrogen is stored or transported. 
     
     
         9 . The method as claimed in  claim 1 , wherein the first sensor element comprises a first semiconductor layer that defines a first opening, and
 wherein the resonant element extends laterally from an edge of the first opening partially over the first opening such that the resonant element hangs over the first opening.   
     
     
         10 . The method as claimed in  claim 9 , further comprising:
 producing a second sensor element in the semiconductor-based layer, the second sensor element forming an acoustic resonator in the semiconductor-based layer; and   forming a second opening in the substrate or in the second sensor element,   wherein the first opening, the acoustic resonator, and the second opening are coupled together to allow a passage of gas to the first sensor element for interacting with the resonant element and to the second sensor element for interacting with the acoustic resonator.   
     
     
         11 . The method as claimed in  claim 10 , wherein a resonance frequency of the acoustic resonator is less than 10 kHz, and
 wherein the resonant element has a resonance frequency greater than 100 kHz.   
     
     
         12 . The method as claimed in  claim 10 , wherein the first sensor element and the second sensor element are formed in sub-layers of the semiconductor-based layer which is arranged between the substrate and the cover. 
     
     
         13 . The method as claimed in  claim 10 , wherein the substrate has the second opening, and
 wherein the cover has a third opening to allow the passage of the gas to the first sensor element for interacting with the resonant element and to the second sensor element for interacting with the acoustic resonator.   
     
     
         14 . The method as claimed in  claim 10 , wherein the acoustic resonator is a chamber that is adjacent to the first opening. 
     
     
         15 . The method as claimed in  claim 10 , wherein the second sensor element comprises a second semiconductor layer that defines the acoustic resonator,
 wherein the first semiconductor layer is coupled to the second semiconductor layer to form a stacked structure that is arranged between the substrate and the cover, and   wherein the first opening, the acoustic resonator, and the second opening are coupled together to allow the passage of the gas between the first opening and the acoustic resonator for the gas to interact with the resonant element and the acoustic resonator.   
     
     
         16 . The method as claimed in  claim 15 , wherein the resonant element extends laterally over the acoustic resonator such that the resonant element hangs over the acoustic resonator. 
     
     
         17 . The method as claimed in  claim 15 , wherein the substrate has the second opening,
 wherein the cover has a third opening to allow the passage of the gas, and   wherein the first opening, the acoustic resonator, the second opening, and the third opening are coupled together to allow the passage of the gas between the second opening and the third opening for the gas to interact with the resonant element and the acoustic resonator.   
     
     
         18 . The method as claimed in  claim 17 , wherein the first opening, the acoustic resonator, the second opening, and the third opening are coupled together to allow the passage of the gas to flow through the first opening and the acoustic resonator. 
     
     
         19 . The method as claimed in  claim 10 , wherein the second sensor element is coupled to the first sensor element such that the second sensor element is arranged between the first sensor element and the substrate. 
     
     
         20 . The method as claimed in  claim 10 , wherein the first opening has a first width and the acoustic resonator has a second width that is greater than the first width. 
     
     
         21 . The method as claimed in  claim 10 , wherein the cover and the second sensor element are attached to the first sensor element in a layer stack formation, with the first sensor element and the second sensor element being arranged adjacent to each other, and the cover being arranged on the first sensor element, and
 wherein the substrate, the second sensor element, the first sensor element, and the cover are coupled together in a vertical stack.   
     
     
         22 . The method as claimed in  claim 10 , wherein the resonant element extends laterally over the acoustic resonator such that the resonant element hangs over the acoustic resonator.